Since ozone exhibits a strong oxidizing action, it has been used in many fields such as water treatment, medical and food industries in recent years, in order to perform deodorization, disinfection and the like. Lately, attention has been paid to ozone for use in various countermeasures for odors in living spaces, and many apparatuses using ozone have been developed.
As described above, ozone exhibits such useful action. However, ozone itself has special odor. Therefore, when ozone is used for an apparatus, it is necessary to prevent ozone from being discharged to the outside of the apparatus. For this reason, ozone remaining after treatment is subjected to a thermal decomposition method or a decomposition method with a catalyst. Among these methods, the method with the catalyst is relatively simple, and thus generally used. However, in the method of decomposing ozone by using the catalyst, there is apprehension that the activity of the catalyst lowers gradually, and ozone in an excessive concentration is discharged to the outside of the apparatus after use for a long period of time or because of changes in environmental conditions or the like.